// https://leetcode.cn/problems/unique-paths-ii/?envType=study-plan-v2&envId=top-interview-150

class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
        int m = obstacleGrid.size();
        int n = obstacleGrid[0].size();

        vector<vector<int>> dp(m, vector<int>(n, 0));
        dp[0][0] = obstacleGrid[0][0] != 1 ? 1 : 0;
        
        for (int i = 1; i < n; i++) {
            if (obstacleGrid[0][i] == 1) {
                break;
            }
            dp[0][i] = dp[0][i - 1];
        }

        for (int i = 1; i < m; i++) {
            if (obstacleGrid[i][0] == 1) {
                break;
            }
            dp[i][0] = dp[i - 1][0];
        }

        for (int i = 1; i < m; i++) {
            for (int j = 1; j < n; j++) {
                if (obstacleGrid[i][j] == 1) {
                    continue;
                }

                dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
            }
        }
        return dp[m - 1][n - 1];
    }
};